High-sensitivity fiber optic temperature sensor based on CTFBG-FPI and Vernier effect

Area of Science:

• Fiber optics
• Optical sensing
• Interferometry

Background:

• Fiber Bragg gratings (FBGs) are widely used in optical sensing.
• Fabry-Perot interferometers (FPIs) offer high sensitivity but can be complex to fabricate.
• The Vernier effect enhances the sensitivity of interferometric systems.

Purpose of the Study:

• To propose and demonstrate a novel high-sensitivity temperature sensor.
• To leverage the Vernier effect for improved temperature sensing performance.
• To develop a sensor for precision temperature measurement applications.

Main Methods:

• Fabrication of two chirped thin-core fiber Bragg grating Fabry-Perot interferometers (CTFBG-FPIs) using femtosecond laser direct writing.
• Inscribing CTFBG-FPIs with different cavity lengths (2 mm and 1.98 mm) to create a Vernier effect system.
• Utilizing staggered CTFBGs with a FWHM of 66.5 nm.

Main Results:

• Demonstration of a high-sensitivity temperature sensor based on CTFBG-FPI and Vernier effect.
• Measurement of a temperature sensitivity of -1.084 nm/°C within the 40-90°C range.
• Successful implementation of a reference arm (2 mm) and a sensing arm (1.98 mm).

Conclusions:

• The proposed CTFBG-FPI sensor with Vernier effect exhibits high sensitivity.
• The sensor is suitable for precision temperature measurement.
• Femtosecond laser direct writing is an effective technique for fabricating such devices.